using sed to copy lines and delete characters from the duplicates

Question

I have a file that looks like this:

@"Afghanistan.png",
@"Albania.png",
@"Algeria.png",
@"American_Samoa.png",

I want it to look like this

@"Afghanistan.png",
@"Afghanistan",
@"Albania.png",
@"Albania",
@"Algeria.png",
@"Algeria",
@"American_Samoa.png",
@"American_Samoa",

I thought I could use sed to do this but I can't figure out how to store something in a buffer and then modify it.

Am I even using the right tool?

Thanks

Answer 1

You don't have to get tricky with regular expressions and replacement strings: use sed's p command to print the line intact, then modify the line and let it print implicitly

sed 'p; s/\.png//'

Answer 2

Glenn jackman's response is OK, but it also doubles the rows which do not match the expression.

This one, instead, doubles only the rows which matched the expression:

sed -n 'p; s/\.png//p'

Here, -n stands for "print nothing unless explicitely printed", and the p in s/\.png//p forces the print if substitution was done, but does not force it otherwise